Make position a native animated value on initialization to fix https://github.com/react-navigation/react-navigation/issues/4886

packages/stack/src/views/Transitioner.js

@@ -1,9 +1,18 @@
 import React from 'react';
-import { Animated, Easing, StyleSheet, View } from 'react-native';
+import {
+  Animated,
+  NativeModules,
+  Easing,
+  StyleSheet,
+  View,
+} from 'react-native';
 import invariant from '../utils/invariant';
 
 import NavigationScenesReducer from './ScenesReducer';
 
+const NativeAnimatedModule =
+  NativeModules && NativeModules.NativeAnimatedModule;
+
 // Used for all animations unless overriden
 const DefaultTransitionSpec = {
   duration: 250,
@@ -38,6 +47,10 @@ class Transitioner extends React.Component {
       ),
     };
 
+    if (NativeAnimatedModule) {
+      this.state.position.__makeNative();
+    }
+
     this._prevTransitionProps = null;
     this._transitionProps = buildTransitionProps(props, this.state);
     this._isMounted = false;